Fiber Bundle for Artificial Hair and Head Decoration Article Comprising the Same

ABSTRACT

To provide fibers for artificial hair prepared under a low nozzle pressure with little gumming, and a fiber bundle for artificial hair having a soft touch close to human hair, while maintaining uniform curling. 
     A fiber bundle for artificial hair comprising fibers (A) having a flexural rigidity of (1.2 to 3.5)×10 −2  N·cm 2  as determined by the KES method and fibers (B) having a flexural rigidity of (0.5 to 1.0)×10 −2  N·cm 2  as determined by the KES method, wherein both of the fibers (A) and the fibers (B) are made of vinyl chloride fibers. The fiber bundle for artificial hair, wherein the content of the fibers (A) is from 30 to 90 mass %, the sectional shape of the fibers (A) is at least one selected from the group consisting of Y-, U- and C-shapes, and the sectional shape of the fibers (B) is a spectacled sectional shape.

TECHNICAL FIELD

The present invention relates to a fiber bundle of artificial hair to be used for hair decoration articles such as wigs, hairpieces, braided hair, extension hair, accessory hair or doll hair, and a head decoration article employing it. Units such as “parts” and “%” showing a blend composition of a resin composition will be represented by mass unless otherwise specified.

BACKGROUND ART

Vinyl chloride resin fibers obtained by spinning a vinyl chloride resin are excellent in transparency and flexibility and thus are widely used as fibers for artificial hair to be used for head decoration articles such as wigs. For industrial production of vinyl chloride resin fibers, a wet spinning method of spinning a vinyl chloride resin by using an organic solvent, a dry spinning method or a melt spinning method of melt-spinning it without using an organic solvent, has been known.

The melt spinning method is a method of extruding the resin at a high temperature under a high pressure by using an extruder. A vinyl chloride resin has a high melt viscosity and an extremely low spinning property, and thus, there has been a problem such that it is difficult to melt-spin the vinyl chloride resin to obtain vinyl chloride resin fibers having a prescribed quality.

As an industrial process, strands are extruded from nozzle holes having a small sectional area per hole, introduced into a heating cylinder and heat-melted and drawn therein to obtain unstretched fibers. However, they are discharged from nozzle holes having a small sectional area per hole, whereby there has been a problem that the pressure exerted to the nozzles tends to be high and is likely to exceed the pressure designed for the extruder, or there has been a problem such that gumming (scales around the nozzles) is likely to result. In order to solve such problems, a means to incorporate a plasticizer and a vinyl chloride homopolymer having a low degree of polymerization has been proposed (e.g. Patent Document 1).

Further, fiber bundles for artificial hair processed by using the above-mentioned fibers for artificial hair, are used as head decoration articles. Such fiber bundles for artificial hair are selected from those wherein the sectional shape of fibers is circular, oval, horseshoe, a cocoon-shape, a ribbon-shape or a star-shape, depending upon the properties such as the touch, the appearance, the gloss and the esthetic functionality attributable to human hair. Further, the head decoration articles are generally classified into three styles of short, medium and long, and the required functions are different depending upon the styles. It has been common to modify the sectional shape of fibers to meet such requirements. However, with a single sectional shape, it has been impossible to meet the requirements of a wide range of hairstyles.

In order to improve uniformity of curling to meet such requirements, a method to have a three-pronged sectional shape (e.g. Patent Document 2), a method to have a hollow section (e.g. Patent Document 3) or a method of mixing fibers having three types of sectional shapes (e.g. Patent Document 4) has been proposed.

Patent Document 1: JP-A-11-61555

Patent Document 2: JP-U-58-37961

Patent Document 3: JP-U-63-48652

Patent Document 4: JP-B-58-13641

DISCLOSURE OF THE INVENTION Object to be Accomplished by the Invention

It is an object of the present invention to provide a fiber bundle for artificial hair having a soft touch close to human hair while maintaining uniform curling, by using fibers for artificial hair prepared under a low nozzle pressure with little gumming and by mixing a plurality of fibers different in the sectional shape of the fibers for artificial hair, and a head decoration article comprising such a fiber bundle.

Means to Accomplish the Object

The present inventors have conducted an extensive study to accomplish the above object and as a result, have found that by mixing fibers having rigidities within certain ranges, a fiber bundle for artificial hair employing fibers for artificial hair made of vinyl chloride fibers, exhibits merits as a head decoration article effectively. Further, it has been found that as the above vinyl chloride fibers, fibers for artificial hair prepared under a low nozzle pressure with little gumming, are obtainable by melt-spinning a specific ethylene/vinyl chloride copolymer resin.

The present invention has been made on the basis of the above discoveries and provides the following.

(1) A fiber bundle for artificial hair comprising fibers (A) having a flexural rigidity of (1.2 to 3.5)×10⁻² N cm² as determined by the KES method and fibers (B) having a flexural rigidity of (0.5 to 1.0)×10⁻² N cm² as determined by the KES method, wherein both of the fibers (A) and the fibers (B) are made of vinyl chloride fibers. (2) The fiber bundle for artificial hair according to the above (1), wherein the content of the fibers (A) is from 30 to 90 mass %. (3) The fiber bundle for artificial hair according to the above (1) or (2), wherein the sectional shape of the fibers (A) is at least one selected from the group consisting of Y-, U- and C-shapes. (4) The fiber bundle for artificial hair according to any one of the above (1) to (3), wherein the sectional shape of the fibers (B) is a spectacled sectional shape. (5) The fiber bundle for artificial hair according to any one of the above (1) to (4), wherein the vinyl chloride fibers are made of fibers prepared by melt spinning an ethylene/vinyl chloride copolymer resin having an ethylene content of from 0.5 to 3 mass %. (6) The fiber bundle for artificial hair according to the above (5), wherein the viscosity-average polymerization degree of the ethylene/vinyl chloride copolymer resin is from 900 to 2,500. (7) The fiber bundle for artificial hair according to the above (5) or (6), wherein the vinyl chloride fibers are made of fibers prepared by melt spinning a mixed resin of the ethylene/vinyl chloride copolymer resin and a vinyl chloride resin other than the ethylene/vinyl chloride copolymer resin. (8) The fiber bundle for artificial hair according to the above (7), wherein the content of the vinyl chloride resin in the mixed resin is at most 40 mass %. (9) The fiber bundle for artificial hair according to the above (7) or (8), wherein the viscosity-average polymerization degree of the vinyl chloride resin is from 600 to 2500. (10) A head decoration article comprising the fiber bundle of artificial hair as defined in any one of the above (1) to (9).

Effects of the Invention

According to the present invention, it is possible to easily obtain fibers for artificial hair prepared under a low nozzle pressure with little gumming, and it is further possible to obtain a fiber bundle for artificial hair having a soft touch close to human hair, while maintaining uniform curling.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view of a nozzle shape for fibers having a Y-shape cross section and the obtained fibers, representing one embodiment of the fiber bundle for artificial hair of the present invention.

FIG. 2 is a is a schematic sectional view of a nozzle shape for fibers having a U-shape cross section and the obtained fibers, representing one embodiment of the fiber bundle for artificial hair of the present invention.

FIG. 3 is a schematic sectional view of a nozzle shape for fibers having a C-shape cross section and the obtained fibers, representing one embodiment of the fiber bundle for artificial hair of the present invention.

FIG. 4 is a schematic sectional view of a nozzle shape for fibers having a spectacled-shape cross section and the obtained fibers, representing one embodiment of the fiber bundle for artificial hair of the present invention.

FIG. 5 is a schematic sectional view of a nozzle shape for fibers having an oval spectacled-shape cross section and the obtained fibers, representing one embodiment of the fiber bundle for artificial hair of the present invention.

FIG. 6 is a schematic sectional view of a nozzle shape for fibers having a five leaf-shape cross section and the obtained fibers, representing one embodiment of the fiber bundle for artificial hair of the present invention.

FIG. 7 is a schematic sectional view of a nozzle shape for fibers having a rod-shape cross section and the obtained fibers, representing one embodiment of the fiber bundle for artificial hair of the present invention.

MEANINGS OF SYMBOLS

-   -   11: Radius of inscribed circle     -   12: Radius of circumscribed circle

BEST MODE FOR CARRYING OUT THE INVENTION Vinyl Chloride Fibers

The fiber bundle for artificial hair of the present invention is composed of vinyl chloride fibers prepared by melt spinning a vinyl chloride resin. The vinyl chloride resin may be obtained by e.g. bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization. However, in consideration of e.g. the initial coloration of fibers, it is preferred to use ones prepared by suspension polymerization. The vinyl chloride resin may be a homopolymer resin which is a conventional homopolymer of vinyl chloride or various types of conventional copolymer resins and is not particularly limited. The copolymer resins are conventional copolymer resins including, for example, a copolymer resin of vinyl chloride with a vinyl ester, such as a vinyl chloride/vinyl acetate copolymer resin or a vinyl chloride/vinyl propionate copolymer resin, a copolymer resin of vinyl chloride with an acrylate, such as a vinyl chloride/butyl acrylate copolymer resin or a vinyl chloride/2-ethylhexyl acrylate copolymer resin, a copolymer resin of vinyl chloride with an olefin such as a vinyl chloride/ethylene copolymer resin or a vinyl chloride/propylene copolymer resin, and a vinyl chloride/acrylonitrile copolymer resin.

It is particularly preferred to use a homopolymer resin which is a homopolymer of vinyl chloride, or a vinyl chloride/vinyl acetate copolymer resin. In the copolymer resin, the content of the comonomer is not particularly limited and may be determined depending upon the required product quality such as the molding processability, fiber properties, etc.

The vinyl chloride resin to be used in the present invention is preferably a homopolymer resin which is a homopolymer of vinyl chloride, a vinyl chloride/ethylene copolymer resin or a vinyl chloride/vinyl acetate copolymer resin. In the copolymer resin, the content of the comonomer is not particularly limited and may be determined depending upon the required product quality such as the molding processability, fiber properties, etc.

The viscosity average polymerization degree of the vinyl chloride resin is preferably from 600 to 2,500, more preferably from 900 to 2,500, particularly preferably from 1,000 to 2,000. If it is less than 600, the melt viscosity tends to be low, and the obtained fibers tend to be susceptible to thermal shrinkage. On the other hand, if it exceeds 2,500, the melt viscosity tends to be high, and the molding temperature of the fibers tends to be high, whereby coloration of fibers may sometimes result. Here, the viscosity average polymerization degree is one calculated by JIS K6720-2 by dissolving 200 mg of the resin in 50 ml of nitrobenzene and measuring the specific viscosity of this polymer solution in a constant temperature tank of 30° C. by using a Ubbelohde viscometer.

The vinyl chloride fibers are particularly preferably fibers prepared by melt spinning an ethylene/vinyl chloride copolymer resin having an ethylene content of from 0.5 to 3 mass %. Such an ethylene/vinyl chloride copolymer resin is a copolymer resin obtainable by a polymerization reaction of vinyl chloride monomer with ethylene monomer, wherein the ethylene content is from 0.5 to 3 mass %, preferably from 0.8 to 2.5 mass %. If the ethylene content is less than 0.5 mass %, the effect to suppress the nozzle pressure and gumming tends to be hardly obtainable. On the other hand, if it exceeds 3 mass %, the fibers tend to be susceptible to thermal shrinkage. The ethylene content is measured in accordance with the GTP-002 method.

Further, in the present invention, a resin composition having the above-mentioned ethylene/vinyl chloride copolymer resin mixed with a vinyl chloride resin other than the ethylene/vinyl chloride copolymer resin, is subjected to melt spinning, whereby it is possible to impart the curl-retaining property to the fibers. The proportion of the vinyl chloride resin mixed is preferably at most 40 mass %, more preferably at most 35 mass %. If the proportion of the vinyl chloride resin exceeds 40 mass %, the effect to suppress gumming at the time of melt spinning may not sometimes be obtainable.

In the present invention, to the above resin composition, known compounding agents may be incorporated, such as a thermal stabilizer, a processing aid, a reinforcing agent, an ultraviolet absorber, an antioxidant, a plasticizer, an antistatic agent, a filler, a flame retardant and a pigment. Further, a special compounding agent such as a blowing agent, a crosslinking agent, an adhesion-imparting agent, a hydrophilicity-imparting agent, an electrical conductivity-imparting agent or a perfume may also be added, as the case requires, within a range not to impair the purpose of the present invention.

As the above thermal stabilizer, one or more may be selected for use among thermal stabilizers including, for example, a Ca—Zn type thermal stabilizer, a hydrotalcite type thermal stabilizer, a tin type thermal stabilizer and a zeolite type thermal stabilizer. It is particularly preferred to use a combination of a Ca—Zn type thermal stabilizer and a hydrotalcite type thermal stabilizer, which is excellent in balance of the molding processability and fiber properties, and it is preferred to use such a combination in an amount of from 0.5 to 5.0 parts by mass per 100 parts by mass of the vinyl chloride resin.

As the above plasticizer, one or more may be selected fro use among plasticizers including, for example, an epoxy plasticizer, a phthalic acid plasticizer, an adipic acid plasticizer, a polyester plasticizer, a phosphate plasticizer, a stearic acid plasticizer, a trimellitic acid plasticizer and a pyromellitic plasticizer. Particularly preferred is an epoxy plasticizer which is less influential over the elongation, and it is preferred to use such a plasticizer in an amount of from 0.2 to 3.0 parts by mass per 100 parts by mass of the vinyl chloride resin.

In the present invention, a lubricant may be used depending upon the purpose. As such a lubricant, a conventional one may be used, but it may particularly be one or a mixture of at least two selected from a metal soap type lubricant, a higher fatty acid type lubricant and a polyethylene type lubricant. The metal soap type lubricant may, for example, be a metal soap such as a stearate, laurate or oleate of e.g. Na, Ca, Zn, Ba or Mg. The higher fatty acid type lubricant may, for example, be a fatty acid ester of an alcohol or a polyhydric alcohol, such as hydrogenated oil, butyl stearate, stearic acid monoglyceride, pentaerythritol tetrastearate or stearyl stearate. The polyethylene type lubricant is not particular limited, and a known lubricant may be used. Particularly preferred is a high density polyethylene lubricant having an average molecular weight of from 2,000 to 6,000 and density of from 0.95 to 0.98.

Fiber Bundle for Artificial Hair

In the present invention, to maintain curling to be uniform, rigidity in the fiber bundle state is required. However, only with fibers having strong rigidity, curling may be made to be uniform, but the soft touch required for the fiber bundle tends to be inferior. On the other hand, only with soft fibers having weak rigidity, the touch may be excellent, but uniform curling as a head decoration article tends to be inferior. By mixing fibers having strong rigidity and fibers having weak rigidity, it is possible to obtain a fiber bundle for artificial hair having a soft touch close to human hair while maintaining uniform curling, taking the advantages of both fibers. Fibers (A) having sectional shapes Y-, U- and C-shapes have a high symmetry in their sectional shapes, and in the same fineness, they have a porosity higher than fibers (B) having a spectacled sectional shape, whereby their rigidity is high, and they are suitable to obtain more uniform curling.

Here, with respect to the rigidity, a flexural rigidity is measured by e.g. the KES method. The KES method is an abbreviation of Kawabata Evaluation System and is designed to measure the repulsion at each curvature when the fibers were flexed by means of a flexural property measuring apparatus (manufactured by KATO TECH CO., LTD.) by the KES method as disclosed by Sueo Kawabata in the journal of Textile Machinery Society (Textile Engineering), vol. 26, No. 10, p. 721-p. 728 (1973). And, an average value of repulsion per fiber between a curvature of 0.5 (cm⁻¹) to a curvature of 1.5 (cm⁻¹). By measuring the repulsion per fiber, the rigidity of the fiber bundle is predictable.

As a method for controlling the value of the flexural rigidity by the KES method, it is possible to adopt, for example, a method of controlling the spinneret temperature of nozzles at the time of melt-spinning fibers (A) and (B). Although the reason is not clearly understood, it is possible to lower the flexural rigidity by lowering the spinneret temperature of the nozzles.

Further, such control can be attained by changing the fineness of the fiber. Namely, by reducing the fineness, the flexural rigidity can be made low. On the other hand, by enlarging the fineness, the flexural rigidity can be made high.

In the present invention, the flexural rigidity of fibers (A) by the KES method is (1.2 to 3.5)×10⁻² N·cm², preferably (1.8 to 2.5)×10⁻² N·cm². Further, the flexural rigidity of fibers (B) by the KES method is (0.5 to 1.0)×10⁻² N·cm², preferably (0.7 to 0.8)×10⁻² N·cm². If the flexural rigidity of fibers (A) by the KES method is smaller than 1.2×10⁻² N cm², the curling uniformity tends to be inferior, and if it exceeds 3.5×10⁻² N·cm², the touch tends to be hard, such being not suitable for a fiber bundle for artificial hair. Further, if the flexural rigidity of fibers (B) by the KES method is less than 0.5×10⁻² N·cm², the curling uniformity tends to be inferior, and if it exceeds 1.0×10⁻² N·cm², the touch tends to be hard, such being not suitable for a fiber bundle for artificial hair.

The fibers (A) and the fibers (B) are preferably vinyl chloride fibers made of a vinyl chloride resin. The vinyl chloride fibers resemble natural hair in the gloss, strength, elongation and specific gravity, and their touch is soft, whereby they are preferred as a fiber bundle for artificial hair.

As the vinyl chloride resin constituting the vinyl chloride fibers, one having the above-described construction and physical properties can be suitably employed.

In the present invention, by adjusting the mixing ratio of fibers (A) and fibers (B), it is possible to obtain more preferred uniform curling and soft touch. If the fibers (A) exceed 90 mass %, the touch tends to be hard, and if they are less than 30 mass %, the uniformity of curling tends to be poor. In a case where a more tight uniformity of curling is required, the fibers (A) are more preferably from 80 to 50 mass %.

Mixing of the fibers (A) and (B) may be carried out during the spinning or at the time of secondary processing. However, in order to obtain a uniform blend to attain the gloss and tough like natural hair, it is preferred to mix them during spinning from mixed nozzles (circular spinneret) wherein a number of nozzles for fibers (A) and (B) are disposed.

Cross-Sectional Shape of Fibers

The sectional shape of the fibers (A) is at least one selected from the group consisting of Y-, U- and C-shapes. These sectional shapes are highly symmetric and have a porosity relatively larger than e.g. a circular shape at the same fineness, and thus they are suitable to obtain high rigidity and more uniform curling.

Y-shape is a shape having three projections radially extending from the center portion in the cross section of a fiber and represents, for example, the shape shown in FIG. 1. The lengths of the projections may be the same or different and may have a dent of recess. The angle θ between the projections is preferably from 90 to 140°, more preferably from 110 to 130°. Further preferably, the cross-sectional shape is such that the total angle of three θ becomes 360°, and the radius of the circumscribed circle becomes from 2 to 4 times the radius of the inscribed circle.

U-shape is a semi-hollow shape with a circular arc having an opening, in the cross section of a fiber and represents, for example, the shape shown in FIG. 2. The thickness of the circular arc portion may be the same or varied and may be asymmetric, and the ends of the opening may be rounded or angular. Further, the width of the opening is preferably the same as the diameter of the center portion of the hollow.

C-shape represents a fiber having an “opened hollow” sectional shape perpendicular to the longitudinal axis of the fiber and having a circular arc in the cross section of the fiber. The “opened hollow” represents a generally C-shaped section having the center portion of the hollow and the solid region extending around the center portion to define the wall portion surrounding the center portion, and the opening on one side of the wall portion connects the center portion to the outside of the fiber. The opening is narrower than the diameter of the center portion of the hollow, whereby a throat or narrowed portion is formed between the center portion of the hollow and the outside of the fiber. It represents, for example, the shape shown in FIG. 3. The thickness of the circular arc portion may be the same or varied and may be asymmetric, and the ends of the opening may be rounded or angular.

The sectional shape of the fibers (B) is preferably a spectacled shape, and the spectacled shape is suitable for a fiber bundle for artificial hair, since not only a soft touch like natural hair is thereby obtainable, but also a plastic-like gloss is thereby little. Here, the spectacled shape is a shape having two circles or ellipses continuously positioned and connected by a bridge, and it represents, for example, the spectacled shape of FIG. 4 or an ellipsoidal spectacled shape of FIG. 5. The circles or the ellipses may have a dent or recess, and the centers of the circles or the ellipses and the center of the connecting portion may be in parallel or not in parallel. However, the connecting bridge is preferably the same as or up to 1.8 times the radius of the circles or the half of the average of the long axis and short axis of the ellipses, and the contact points of the bridge with the circles are preferably always curved in an arc. Further, the continuous circles are preferably adjacent to each other to such an extent that the arcs of the circles are in contact with each other, and ones which are extremely apart from each other or ones of which the arcs overlap each other are not desirable.

Process for Producing Fiber Bundle for Artificial Hair

A vinyl chloride resin composition as the starting material may be used in the form of a powder compound prepared by mixing by means of a conventional mixing machine such as a Henschel mixer, a super mixer or a is ribbon blender, or in the form of a pellet compound prepared by melt-mixing such a powder compound.

The powder compound may be prepared under conventional conditions, and the preparation may be hot blending or cold blending. Particularly preferably, hot blending is used wherein the cutting temperature at the time of blending is raised to a level of from 105 to 155° C. in order to reduce the volatile component in the resin composition.

The pellet compound can be prepared in the same manner as the preparation of a usual vinyl chloride type pellet compound. For example, by using a kneader such as a single screw extruder, a counter-rotating twin screw extruder, a conical twin screw extruder, a co-rotating twin screw extruder, a co-kneader, a planetary gear extruder or a roll kneader, the pellet compound may be prepared. The conditions for preparing the pellet compound are not particularly limited, but it is preferred to set them so that the resin temperature will be at most 185° C.

The fibers (A) and (B) are preferably processed by melt spinning, and nozzles to be used may suitably be selected taking into consideration the expansion due to the Burns effect at the time when the molten resin is extruded from the nozzles and/or the reduction of the sectional shape due to drawing exerted to the fibers at the time of spinning. Especially in the melt spinning, the polyvinyl chloride resin has a good shaping property, and by using nozzles having a nozzle hole shape close to the sectional shape of the desired fibers of the present invention, the fibers (A) and (B) will be obtained.

In the present invention, melt spinning can be carried out by using conventional nozzles. However, taking into consideration the quality aspect such as the curling property for artificial hair, it is preferred to carry out melt extrusion from nozzles having a sectional area of at most 0.5 mm² per nozzle hole. If the sectional area per nozzle hole exceeds 0.5 mm², it will be required to exert an excessive tension to form a fine non-stretched fiber or stretched fiber, whereby the residual strain will increase, and the product quality such as the curl-retention tends to deteriorate. Therefore, particularly preferably, strands are melt-extruded from a plurality of nozzle holes of multi-type nozzles having a sectional area of at most 0.5 mm² per nozzle hole to produce non-stretched fibers having at most 300 decitex.

Further, non-stretched fibers may be obtained also by melt-spinning a pellet compound or the like, of the resin composition at a temperature of from 160 to 190° C., for example, by using a single screw extruder.

The conditions for stretch treatment are preferably such that the non-stretched fibers are stretched from 2 to 4 times in an atmosphere of air held at a temperature of from 90 to 120° C., and then the stretched fibers are annealed in an atmosphere of air held at a temperature of from 110 to 140° C. until they become to have a length of from 60 to 100% of the length before the annealing. The fibers having stretch treatment and thermal treatment applied to the non-stretched fibers are preferably such that the fineness of each fiber is preferably from 20 to 100 decitex, more preferably from 50 to 80 decitex. When the fineness is from 20 to 100 decitex, the fiber is comparable to natural hair, and when it is from 50 to 80 decitex, it will be one having the touch and texture further improved.

EXAMPLES

Now, the present invention will be described in further detail with reference to Examples, but it should be understood that the present invention is by no means restricted by such Examples.

TABLE 1-1 Comparative Examples Examples 1-1 1-2 1-3 1-1 1-2 Ethylene content 1.5 mass % 0.5 mass % 3.0 mass % 0.3 mass % 4.0 mass % Nozzle pressure Excellent Excellent Excellent No good Excellent Gumming time Excellent Excellent Excellent No good Excellent Thermal Excellent Excellent Good Excellent No good shrinkage

TABLE 1-2 Examples 1-1 1-4 1-5 Polymerization degree of 1300 700 2600 ethylene/vinyl chloride copolymer resin Thermal shrinkage Excellent Good Excellent Coloration Excellent Excellent Good

TABLE 1-3 Examples 1-6 1-7 Vinyl chloride resin 30 mass % 50 mass % content Gumming time Excellent Good Curl-retention Excellent Excellent

TABLE 1-4 Examples 1-6 1-8 1-9 Polymerization degree of 1000 500 2700 vinyl chloride resin Coloration Excellent Excellent Good Thermal shrinkage Excellent Good Excellent

In Table 1-1, the “nozzle pressure” is an index as to whether or not, when continuous spinning is carried out, the spinning can be carried out in a stabilized state for a long period of time. The “nozzle pressure” is a resin pressure measured at nozzles when continuous spinning is carried out for 24 hours, and it was evaluated by the following standards.

Excellent: The nozzle pressure is at most 40 MPa, whereby the production can be constantly carried out, and there is no problem in the long running property. Good: The nozzle pressure is from 40 MPa to 45 MPa, whereby the production can be constantly carried out, and there is no problem in the long running property. No good: The nozzle pressure exceeds 45 MPa, whereby it is necessary to reduce the extruding amount in order to carry out the production constantly.

In Tables 1-1 and 1-3, the “gumming time” is an index for the production time until the production becomes difficult as fiber breakage starts due to gumming and the gumming is wiped off. The “gumming time” was evaluated by the following standards.

Excellent: It is at least 36 hours, whereby the production can be carried out constantly, and there is no problem in the long running property at all. Good: It is from 24 to 36 hours, whereby the production can be carried out constantly, and there is no problem in the long running property. No good: It is less than 24 hours, and there is a problem in the long running property to carry out the production constantly.

In Tables 1-2 and 1-4, the “coloration” is the color of fibers immediately after the continuous spinning, as visually observed, and it was evaluated by the following standards.

Excellent: No yellowing is observed, and there is no problem at all from the viewpoint of the product quality. Good: Yellowing is observed very slightly, but there is no problem from the viewpoint of the product quality. No good: Yellowing is observed, and there is a problem from the viewpoint of the product quality.

In Table 1-3, the “curl-retention” was evaluated under the following standards by putting fibers in a hot air dryer at 90° C. for 60 minutes in a state where the fibers are wound on an aluminum pipe with their forward end fixed, thereafter taking them out, suspending them for 24 hours in a state at a temperature of 23° C. under a relative humidity of 50° C., and measuring the distance of the movement of the suspended forward end before and after the suspension. The shorter the distance of this movement, the better the curl-retention.

Excellent: The distance of movement of the forward end is at most 1.5 cm. Good: The distance of movement of the forward end is more than 1.5 cm and less than 3.0 cm. No good: The distance of movement of the forward end is at least 3.0 cm.

In the Tables 1-1, 1-2 and 1-4, the “thermal shrinkage” means the thermal shrinkage which takes place when a test specimen is thermally treated. The test for the thermal shrinkage is carried out by subjecting a test sample adjusted to a length of 100 mm to thermal treatment for 15 minutes in a gear oven of 90° C. and measuring the length of the test sample before and after the thermal treatment. The thermal shrinkage is obtained from the obtained length by the following formula.

Thermal shrinkage (%)=difference in length of test sample before and after thermal treatment/length of test sample before thermal treatment×100

The number of test samples was ten, and the average value was evaluated by the following standards.

Excellent: The average value of thermal shrinkage is at most 5%, whereby there is no problem at all from the viewpoint of the product quality. Good: The average value of thermal shrinkage is more than 5% and less than 10%, and there is no problem from the viewpoint of the product quality. No good: The average value of the thermal shrinkage is at least 10%, whereby there is a problem from the viewpoint of the product quality.

Now, referring to Table 1-1, the present invention will be described in detail with reference to Examples and Comparative Examples. These Examples are exemplary and by no means limit the present invention.

Example 1-1

Fibers for artificial hair having a fineness of 67 decitex were obtained by sequentially carrying out (a) a step of mixing by a Henschel mixer a resin composition prepared by blending 100 parts by mass of an ethylene/vinyl chloride copolymer resin (manufactured by Taiyo Vinyl Corp., TE-1300; ethylene content: 1.5 mass %, viscosity average polymerization degree: 1,300), 8 parts by mass of a hydrotalcite type composite thermal stabilizer (manufactured by Nissan Chemical Industries, Ltd., CP-410A) (thermal stabilizer component being 4 parts by mass %), and 1 part by mass of epoxidized soybean oil (ADECA CORPORATION, 0-130P), (b) a step of melt spinning the mixed resin composition at a spinneret temperature of 180° C. at an extrusion rate of 12 kg/hr by using a spinneret having 120 nozzle holes and a nozzle sectional area of 0.06 mm², to obtain fibers of 150 decitex, (c) a step of stretching the melt-spun fibers 300% in an atmosphere of air at 1000° C. to obtain fibers of 50 decitex, and (d) a step of applying thermal relaxing treatment in an atmosphere of air at 1200° C. until the entire length of fibers shrunk to a length of 75% of the length before the treatment.

Examples 1-2 and 1-3, and Comparative Examples 1-1 and 1-2

Fibers for artificial hair having ethylene contents as identified in Table 1-1 were obtained in the same manner as in Example 1-1.

Examples 1-4 and 1-5

Fibers for artificial hair having the ethylene content adjusted to be 1.5 times of Example 1-1 and having the viscosity average polymerization degree of the ethylene/vinyl chloride copolymer as shown in Table 1-2, were obtained in the same manner as in Example 1-1.

Examples 1-6 and 1-7

Fibers for artificial hair having a vinyl chloride resin content as identified in Table 1-3 were obtained in the same manner as in Example 1-1.

Examples 1-8 and 1-9

Fibers for artificial hair having the vinyl chloride resin content adjusted to be the same as in Example 1-6 and having the viscosity average polymerization degree of the vinyl chloride resin as identified in Table 1-4, were obtained in the same manner as in Example 1-1.

With the fibers for artificial hair of the present invention, the fibers can be constantly produced under a low nozzle pressure with little gumming, and the curl retention is excellent.

TABLE 2-1 Examples 2-1 2-2 2-3 2-4 2-5 2-6 Fibers (A) Flexural 2 2 1.8 1.8 2.2/2   2.5 rigidity (×10⁻²) Sectional Y-shape Y-shape Five-leaf Five-leaf U-shape/ C-shape shape shape shape Y-shape Mass % 70 95 20 20 40/30 70 Fibers (B) Flexural 0.8 0.7 0.8 0.7 0.8 0.8 rigidity (×10⁻²) Sectional Spectacled Rod shape Spectacled Rod shape Spectacled Spectacled shape shape shape shape shape Mass % 30 5 80 80 30 30 Uniformity of curling Excellent Excellent Good Good Excellent Excellent Touch Excellent Good Excellent Good Excellent Excellent Comparative Examples 2-1 2-2 2-3 2-4 2-5 2-6 Fibers (A) Flexural 2 1 4 1.5 3 rigidity (×10⁻²) Sectional Y-shape Y-shape Y-shape Y-shape Y-shape shape Mass % 100 70 70 70 70 Fibers (B) Flexural 0.8 0.65 1.0 0.3 1.5 rigidity (×10⁻²) Sectional Spectacled Spectacled Spectacled Spectacled Spectacled shape shape shape shape shape shape Mass % 100 30 30 30 30 Uniformity of curling Excellent No good No good Good No good Excellent Touch No good Excellent Excellent No good Good No good

TABLE 3-2 Examples Comparative Examples 3-1 3-2 3-3 3-4 3-1 3-2 Fibers (A) Sectional U-shape C-shape Y-shape/ Y-shape U-shape C-shape shape U-shape Mass % 90 25 40/30 95 100 100 Flexural 2.2 2.5   2/2.2 2 2.2 2.5 rigidity (×10⁻²) Fibers (B) Sectional Spectacled Spectacled Spectacled Spectacled shape shape shape shape shape Mass % 10 75 30 5 Flexural 0.8 0.8 0.8 0.8 rigidity (×10⁻²) Uniformity of curling Excellent Good Excellent Excellent Excellent Excellent Touch Good Excellent Excellent Good No good No good

In Tables 2-1 and 3-1, the “flexural rigidity” was measured by using KES-FB2 pure bending tester (manufactured by KATO TECH CO., LTD.). Namely, one fiber having a length of 9 cm, of the fibers (A) or (B), was passed through a jig having a diameter of 0.2 mm and subjected to a pure bending test at a deformation rate of 0.2 (cm⁻¹) within a curvature range of from −2.5 to +2.5 (cm⁻¹), and an average value of repulsion with one fiber within a curvature range of from 0.5 to 1.5 (cm⁻¹) was measured.

In Tables 2-1 and 3-1, the “uniformity of curling” was evaluated by carrying out treatment as follows. Namely, 1 g of a fiber bundle comprising the fibers (A) and (B) and having a length of 60 cm was wound at intervals of 30 mm on an aluminum pipe having a diameter of 30 mm and heated by a dry heat of 850° C. for 1 hour. Then, it was left to stand for 2 hours under a constant temperature condition (20° C., 65 RH %) as it was wound, and then, it was removed from the pipe, and the fiber bundle was suspended. Upon expiration of 24 hours after suspending the fiber bundle having curling imparted, the first and fifth curl pitches from the top were measured and “the difference in curl pitch” was obtained. The results were evaluated by the following standards.

Excellent: The difference in curl pitch is smaller than 10 mm, such being suitable for an article required to have a tight curl. Good: The difference in curl pitch is from 10 to 20 mm, and uniform curling is obtainable. No good: The difference in curl pitch is larger than 20 mm, and curling is non-uniform.

In Tables 2-1 and 3-1, the “tough” represents the touch when 24,000 fibers comprising fibers (A) and (B) are bundled, and the fibers are frictioned one another, and it was evaluated by the following standards.

Excellent: The touch is soft resembling natural hair. Good: The touch is slightly soft resembling natural hair. No good: The touch is stiff and hard.

Example 2-1

Fibers having 160 decitex were obtained by melt spinning a resin composition prepared by blending 100 parts by mass of a vinyl chloride resin (manufactured by Taiyo Vinyl Corp., TH-1000), 3 parts by mass of a hydrotalcite type composite thermal stabilizer (manufactured by Nissan Chemical Industries, Ltd., CP-410A) (thermal stabilizer component being 1.5 parts by mass), 0.5 part by mass of epoxidized soybean oil (manufactured by ADECA CORPORATION, O-130P) and 0.8 part by mass of an ester type lubricant (manufactured by Riken Vitamin Co., Ltd., EW-100) by means of mixed nozzles (circular spinning spinneret having a nozzle section shown in FIG. 1 and a nozzle section shown in FIG. 4, at a spinneret temperature of 170° C. at an extrusion rate of 10 kg/hr. Further, the fibers obtained by the melt spinning were subjected to stretching in an atmosphere of air at 105° C. to 300%. Then, they were thermally treated in an atmosphere of air at 110° C. until the entire length of the fibers shrunk to a length of 75% of the length before the treatment. As a result, Y-sectional shape fibers having a flexural rigidity of 2.0×10⁻² N·cm² and a fineness of 71 decitex as fibers (A) and spectacled sectional shape fibers having a flexural rigidity of 0.8×10⁻² N·cm² and a fineness of 71 decitex as fibers (B) were obtained. The product was a fiber bundle for artificial hair comprising 70 mass % of the fibers (A) and 30 mass % of the fibers (B).

Examples 2-2 to 2-6, and Examples 3-1 to 3-4

Fiber bundles for artificial hair having the sectional shapes and mass % of the fibers (A) and the fibers (B) as identified in Tables 2-1 and 3-1 were obtained in the same manner as in Example 2-1.

Comparative Example 2-1 and Comparative Examples 3-1 and 3-2

Fiber bundles for artificial hair were obtained in the same manner as in Example 2-1 except that the sectional shape of the fibers (A) was Y-shape of FIG. 1 and no fibers (B) were contained.

Comparative Example 2-2

A fiber bundle for artificial hair was obtained in the same manner as in Example 2-1 except that the sectional shape of the fibers (B) was a spectacled shape of FIG. 4 and no fibers (A) were contained.

Comparative Examples 2-3 and 2-4

Fiber bundles for artificial hair were obtained in the same manner as in Example 2-1 except that in Comparative Example 2-3, the spinneret temperature was changed to 160° C., and in Comparative Example 2-4, the spinneret temperature was changed to 180° C.

Comparative Examples 2-5 and 2-6

Fiber bundles for artificial hair were obtained in the same manner as in Example 2-1 except that in Comparative Example 2-5, the fineness of the fibers (A) and the fibers (B) was changed to 100 decitex, and in Comparative Example 2-6, the fineness of the fibers (A) and the fibers (B) was changed to 220 decitex.

As is evident from Tables 2-1 and 3-1, according to the present invention, it is possible to obtain fiber bundles for artificial hair which have a soft touch close to natural hair, while maintaining uniform curling.

INDUSTRIAL APPLICABILITY

The fibers for artificial hair and the fiber bundle for artificial hair of the present invention can be suitably employed for hair decoration articles such as wigs, hairpieces, braids, extension hair, accessory hair and doll hair.

The entire disclosures of Japanese Patent Application No. 2005-176083 filed on Jun. 16, 2005, Japanese Patent Application No. 2005-203957 filed on Jul. 13, 2005 and Japanese Patent Application No. 2005-203958 filed on Jul. 13, 2005 including specifications, claims, drawings and summaries are incorporated herein by reference in their entireties. 

1. A fiber bundle for artificial hair comprising fibers (A) having a flexural rigidity of (1.2 to 3.5)×10⁻² N·cm² as determined by the KES method and fibers (B) having a flexural rigidity of (0.5 to 1.0)×10⁻² N·cm² as determined by the KES method, wherein both of the fibers (A) and the fibers (B) are made of vinyl chloride fibers.
 2. The fiber bundle for artificial hair according to claim 1, wherein the content of the fibers (A) is from 30 to 90 mass %.
 3. The fiber bundle for artificial hair according to claim 1, wherein the sectional shape of the fibers (A) is at least one selected from the group consisting of Y-, U- and C-shapes.
 4. The fiber bundle for artificial hair according to claim 1, wherein the sectional shape of the fibers (B) is a spectacled sectional shape.
 5. The fiber bundle for artificial hair according to claim 1, wherein the vinyl chloride fibers are made of fibers prepared by melt spinning an ethylene/vinyl chloride copolymer resin having an ethylene content of from 0.5 to 3 mass %.
 6. The fiber bundle for artificial hair according to claim 5, wherein the viscosity-average polymerization degree of the ethylene/vinyl chloride copolymer resin is from 900 to
 2500. 7. The fiber bundle for artificial hair according to claim 5, wherein the vinyl chloride fibers are made of fibers prepared by melt spinning a mixed resin of the ethylene/vinyl chloride copolymer resin and a vinyl chloride resin other than the ethylene/vinyl chloride copolymer resin.
 8. The fiber bundle for artificial hair according to claim 7, wherein the content of the vinyl chloride resin in the mixed resin is at most 40 mass %.
 9. The fiber bundle for artificial hair according to claim 7, wherein the viscosity-average polymerization degree of the vinyl chloride resin is from 600 to 2,500.
 10. A head decoration article comprising the fiber bundle of artificial hair as defined in claim
 1. 